Machines have been designed for moulding plastic disk insulators onto an axial conductor during the manufacture of coaxial cables. Such machines made up till now have male and female moulding units constituting links which alternate along two chains of moulding units, such that a stud on a male moulding unit in one of the chains fits into a hollow in a female moulding unit in the other chain and thereby aligns the half-shells of the moulding units in each chain at the instant when they come in front of a plastic injection hole. A male unit in such a machine has a set of inner fixing tabs at each of its ends to engage on the inner sides of fixing tabs at the connecting ends of the adjacent female units. Each pair of engaging tab sets is connected together by a pin.
The result of this is that both of the chains must have an even number of links. This restricts the choice of combinations of units, and it is these combinations which make it possible to limit accumulation of defects due to unevenness in moulding the disk insulators. Such defects degrade the transmission of high-frequency signals much more if both chains have the same number of units, and the effect still remains appreciable even when the two chains differ by an even number of units.
Preferred embodiments of the present invention provide a machine for manufacturing inserts in the shape of disks on a very long rod such that any number of moulding units can be included in each chain, in particular an odd number. Further such embodiments provide a manufacturing machine whose chains of units can differ by an odd number of units and in particular by one unit thereby reducing as far as possible degradation of high-frequency signal transmission due to defects in the moulding units.